1. Field of the Invention
The present invention relates to a ratchet one-way clutch using ratchets (pawls) as a locking mechanism among one-way clutches used in a transmission for motor vehicles, farm machines, building machines, industrial machines and the like and having a back stop function, particularly a transmission for vehicles, and a stator for a torque converter using such a ratchet one-way clutch.
2. Related Background Art
In general, a one-way clutch used in an automatic transmission has outer and inner races which are rotated relative to each other, and sprags or rollers for transmitting torque between the outer race and the inner race are engaged by a track surface of the outer race or the inner race so that rotational torque is transmitted only in one direction. Further, the clutch is idly rotated in an opposite direction.
Among such one-way clutches, there is a ratchet one-way clutch in which a ratchet is used as a torque transmitting member for transmitting torque between the outer race and the inner race. The ratchet one-way clutch is constituted by an outer race provided at its inner periphery with pockets, an inner race disposed in coaxial with the outer race and provided at its outer periphery with notches, pawl members disposed within the pockets and adapted to be fitted into the notches of the inner race to establish a lock-up condition of the one-way clutch in which torque can be transmitted between the inner race and the outer race, and elastic members for biasing the pawl members towards the inner race.
In the ratchet one-way clutch having the above-mentioned arrangement, when the one-way clutch is rotated in one direction, since the pawl members are slid freely with respect to an outer periphery of the inner race, the outer race and the inner race are rotated idly relative to each other. If the one-way clutch tries to rotate in an opposite direction, the pawl members are fitted into the notches, thereby establishing the lock-up condition of the one-way clutch.
In recent years, development regarding compactness, light-weighting and cost reduction of parts of a motor vehicle such as a transmission has widely been effected, and the one-way clutch is also included in such interest. In order to meet such request, use of the ratchet one-way clutch has been proposed.
Generally, in the ratchet one-way clutch, recessed portions formed in the inner race or the outer race engage the pawl members, thereby transmitting the torque. In order to absorb shock generated by fitting the pawl members into the recessed portions, damper springs are provided on an outer periphery of the outer race.
Although the damper springs which are normally coil springs are contained in pockets provided in the outer periphery of the outer race, since the shape of the pocket differs from that of the damper spring, the holding ability and operation reliability of the spring are not always satisfied.
Further, due to the difference between the shape of the damper spring and that of the pocket, a part of the damper spring is slidingly contacted with an inner wall of the pocket, thereby generating local wear.
Accordingly, an object of the present invention is to provide a ratchet one-way clutch which can achieve a holding ability and operating stability of a damper spring and can prevent local wear of the damper spring.
To achieve the above object, the present invention provides a ratchet one-way clutch comprising inner and outer races disposed on a same axis and in which a pawl member as a torque transmitting member and a biasing member for biasing the pawl member are provided in one of the inner and outer races and a recessed portion into which the pawl member is fitted is provided in the other of the inner and outer races and a damper spring is provided on an outer periphery of the outer race and wherein an inner surface of a spring pocket for containing the damper spring has a shape complementary to a shape of the damper spring.
In the present invention, since the inner surface of the spring pocket for containing the damper spring has the shape complementary to the shape of the damper spring, a holding ability and operating stability of the damper spring are enhanced.
Further, due to the difference between the shape of the damper spring and that of the pocket, the part of the damper spring was slidingly contacted with the inner wall of the pocket particularly, thereby generating local wear. However, in the present invention, by adopting complementary shape arrangement, wear can be prevented.